For a first quilt top, it's wise to stay around lap quilt size -- a width of about 52-68 inches, and a length of about 52-78 inches. This will make it easier to stuff under the arm of your sewing machine while you machine quilt. Even if you decide to hand quilt, it's a good idea to keep that first project about this size so you don't feel too bogged down in terms of time needed for the quilting.